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1. (a) Red blood cells are specialised cells that transport oxygen. State the substance in red blood cells that combines with oxygen.
(b) State the name of the component of blood that promotes blood clotting.
(c) Some students investigated the effect of immersing red blood cells in different concentrations of salt solution. They measured the diameters of samples of red blood cells and calculated the mean. They then immersed each red blood cell sample in a different concentration of salt solution. After two minutes they measured and calculated the mean of the samples again.
[Table_1 here]
(i) Calculate the percentage increase in the mean diameter of red blood cells that were immersed in the 0.8\% salt solution. Give your answer to two significant figures.
(ii) Explain the results for the red blood cells that were immersed in the 1.8\% salt solution.
(iii) State why there was no change in the mean diameter of the red blood cells immersed in the 0.9\% salt solution.
(d) State why red blood cells burst when immersed in pure water but plant cells do not.
(e) State two uses of water in a plant.
1 ...........................................................
2 ...........................................................
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2. Fig. 2.1 is a photograph of some leaves of a water lily, which is a hydrophyte. The water lily has adaptive features that are found in many different hydrophytes.
(a) Describe what is meant by an adaptive feature.
[Image_1 here]
(b) Fig. 2.2 is a photomicrograph of a cross-section of a part of a water lily leaf.
[Image_2 here]
(i) State the names of the parts labelled A, B and C in Fig. 2.2.
(ii) Explain how part C in Fig. 2.2 adapts the hydrophyte for its environment.
(c) A scientist calculated the mean number of stomata per mm² in the upper and lower epidermis in tomato plants and water lily plants.
[Table_2 here]
(i) Compare and explain the differences in the mean number of stomata in a tomato plant and in a water lily plant.
(ii) State the name of the cells that control the opening and closing of stomata.
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3. Fig. 3.1 is a diagram of the junction between two neurones in a healthy person. Fig. 3.2 is a diagram of the junction between the same two neurones in a person who has Parkinson’s disease. This disease affects the nervous system.
[Image_3, Image_4 here]
(a) Identify the parts labelled X and Y in Fig. 3.2.
(b) Parkinson’s disease affects neurones in the brain that are responsible for movement. Using the information in Fig. 3.1 and Fig. 3.2, suggest and explain the effect of Parkinson’s disease on a person’s movement.
(c) Describe two ways nervous control differs from hormonal control.
(d) (i) The shape of the receptor proteins shown in Fig. 3.1 and Fig. 3.2 is important for their function. Explain how the shape of the receptor proteins is determined.
(ii) Cell membranes also contain protein carriers. Describe the role of protein carriers.
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4. A scientist investigated the effect of temperature on the rate of photosynthesis in one species of plant. Photosynthesis involves enzyme-controlled reactions. Discs were cut from a leaf and kept at different temperatures. The total surface area of the discs was kept the same for each temperature. The volume of oxygen that was produced by the leaf discs was measured and used to estimate the rate of photosynthesis.
[Graph_1 here]
(a) Identify the optimum temperature for photosynthesis in Fig. 4.1.
(b) Explain the results shown in Fig. 4.1.
(c) Carbon dioxide was supplied in excess at each temperature during the investigation. Explain why.
(d) Suggest why not all of the oxygen produced by the leaf is released.
(e) Describe the role of chlorophyll in photosynthesis.
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5. (a) Describe two ways in which the circulatory system of a fish is different from the circulatory system of a mammal.
(b) Explain the advantages of a double circulatory system.
(c) Fig. 5.1 shows part of the circulatory system of a mammal.
[Image_5 here]
(i) State the letter from Fig. 5.1 that identifies where these processes occur:
absorption of the products of digestion into the blood ............................................................
excretion of carbon dioxide from the body ...........................................................
formation of urine ...........................................................
production of bile. ...........................................................
(ii) Identify the name of the blood vessel labelled X in Fig. 5.1.
(d) Describe the role of the liver in excretion.
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6. (a) State the names of two hormones released by the ovaries.
(b) During pregnancy, antibodies are acquired by the fetus from the mother. State the organ the antibodies cross to reach the fetus.
(c) A baby was breastfed for six months. The concentration of antibodies in the baby’s blood obtained from breast milk and the concentration of antibodies made by the baby itself were measured.
[Graph_2 here]
(i) Complete the sentences to describe the changes in antibody concentration in the baby.
After birth the concentration of antibodies acquired from the mother decreases rapidly to 0 arbitrary units at ................................................ months.
Antibodies start being produced by cells called ................................................ in the baby immediately after birth.
The total concentration of antibodies in the baby from both sources is ..................................... arbitrary units at 4 months.
The concentration of antibodies acquired from the mother and the concentration of antibodies produced by the baby are the same at ...................................... months.
(ii) Describe the benefits of breastfeeding a baby for the first six months of life.
(iii) State two ways, other than breastfeeding, that a baby can acquire immunity.
(d) Explain the importance of the shape of an antibody.
(e) Antibodies are proteins. State the chemical elements present in all proteins that are also found in carbohydrates and fats.
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